Re: [PATCH v3 1/6] ldbl-128ibm-compat: workaround GCC 9 C++ BZ 90731

[Paul E Murphy <murphyp@linux.ibm.com>]

On 4/22/20 10:11 AM, Florian Weimer wrote:
> * Paul E. Murphy via Libc-alpha:
> 
>> GCC 9 has a bug (BZ 90731) whereby __typeof does not correctly copy
>> exception specifiers[1].  Surprisingly, this can be quieted by declaring
>> "#pragma system_header", or if the headers are installed in a system
>> directory.
> 
> I think GCC developers prefer “PR90731” to their bugs.  This occurs
> multiple times in the commit message and throughout the patch.

Ack.  Will fix here and in the subsequent patches too.

> 
> This change will still cause errors with -Wsystem-headers in the build
> flags, right?  I think we should mention this somewhere, maybe on the
> release wiki?
> 

Unfortunately, ppc64le glibc will fail to build with GCC 9.2.0 with this 
option irrespective of this feature.  Though, you are correct the 
redirects will generate additional warnings when used with such toolchains.

Likewise, --disable-werror does avoid breaking things when using 
-Wsystem-headers.  The warnings are not fatal.

I suspect the -Wsystem-headers will cause some noise for most users with 
GCC 8/9 and likely others.  I can add a note, but I suspect I will need 
to be granted wiki editing privileges.